A power amplifier for radar applications which keeps output electric power in a pulse at a constant value and is often operated by maximum electric output power is often composed by a class-C power amplifier, in order to operate with a high degree of efficiency. However, in order to increase the efficiency of a class-C operation, load impedance for higher order harmonics must be short-circuited based on theory. Therefore, the degree of difficulty in achieving broader bandwidths is great.
A power amplifier for communication applications of which high linearity is required is often composed by a nonlinear class-B power amplifier to such an extent that distortion can be compensated in linearizer. This is because the class-B power amplifier is operated with a degree of efficiency lower than a class-C power amplifier, but the class-B power amplifier can be operated with a degree of efficiency higher than a class-A power amplifier. However, in order to also increase the efficiency of a class-B operation, load impedance for higher order harmonics must be short-circuited based on theory. Therefore, the degree of difficulty in achieving the broader bandwidths was great.
On the other hand, the class-J/B operation received attention recently can achieve efficiency equivalent to the class-B operation over the broader bandwidths.
Although the class-B power amplifier can achieve the broader bandwidths, the class-B power amplifier is operated with a degree of efficiency lower than the class-C power amplifier. On the other hand, although the class-C power amplifier can be operated with a degree of efficiency higher than the class-B power amplifier, its bandwidth is narrow.